dotnet/wpf · error · ArgumentException

SR.Image_CantBeFrozen

Error message

SR.Image_CantBeFrozen

What it means

The BitmapVisualManager constructor throws ArgumentException with SR.Image_CantBeFrozen when the supplied RenderTargetBitmap is frozen (Freezable.IsFrozen == true). A frozen target is immutable, so a manager whose purpose is to render into it cannot work.

Solutions

1. Pass a mutable (non-frozen) RenderTargetBitmap to the constructor.
2. Do not Freeze() the bitmap if it will be a render target; freeze only copies/outputs.
3. Clone the frozen bitmap (RenderTargetBitmap.Clone()) if you need a writable copy for rendering.

Example fix

// before
bitmap.Freeze();
var mgr = new BitmapVisualManager(bitmap); // throws
// after
var mgr = new BitmapVisualManager(bitmap); // keep mutable while rendering
// ... render ...
bitmap.Freeze(); // only after rendering completes

if (bitmapTarget == null) throw new ArgumentNullException(nameof(bitmapTarget));
if (bitmapTarget.IsFrozen)
    throw new ArgumentException("render target must not be frozen", nameof(bitmapTarget));

bool IsRenderable(RenderTargetBitmap bmp) => bmp != null && !bmp.IsFrozen;

try { var mgr = new BitmapVisualManager(rtBitmap); } catch (ArgumentException) { rtBitmap = rtBitmap.Clone(); var mgr = new BitmapVisualManager(rtBitmap); }

When it happens

Trigger: new BitmapVisualManager(someRenderTargetBitmap) where the bitmap was frozen via Freeze() or obtained from a frozen/shared freezable resource.

Common situations: Sharing a cached RenderTargetBitmap declared in a resource dictionary with freeze enabled, or explicitly freezing for thread-safety before handing it to the manager.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• Current DocumentSequence, FixedDocument, or FixedPage not…
• IAmbientProvider
• IAnimatable_CantAnimateSealedDO
• Image_EncoderNoColorContext
• Image_EncoderNoGlobalMetadata

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/eed32d5fafad49c1. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/Media/Imaging/BitmapVisualManager.cs:32

    /// </summary>
    internal class BitmapVisualManager : DispatcherObject
    {
        #region Constructors
        private BitmapVisualManager()
        {
        }

        /// <summary>
        /// Create an BitmapVisualManager for drawing a visual to the bitmap.
        /// </summary>
        /// <param name="bitmapTarget">Where the resulting bitmap is rendered</param>
        public BitmapVisualManager(RenderTargetBitmap bitmapTarget)
        {
            ArgumentNullException.ThrowIfNull(bitmapTarget);

            if (bitmapTarget.IsFrozen)
            {
                throw new ArgumentException(SR.Format(SR.Image_CantBeFrozen, null));
            }

            _bitmapTarget = bitmapTarget;
        }

        #endregion

        #region Public methods
        /// <summary>
        /// Render visual to printer.
        /// </summary>
        /// <param name="visual">Root of the visual to render</param>
        public void Render(Visual visual)
        {
            Render(visual, Matrix.Identity, Rect.Empty);
        }

        /// <summary>

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